MSD function and selection of power battery system

What functions does the MSD need to have in order to ensure the safety of the power battery pack. The MSD in the power battery system Pack has gradually changed from an optional configuration to a standard configuration. This process is not too long. For more reliable use and maintenance of the safety performance, some factors need to be considered when selecting the MSD; 1.MSD Briefly describe the full English name of MSD: ManualServiceDisconnect; Chinese name: Manual Maintenance Switch. The main function of MSD: In order to protect the safety of technicians who repair electric vehicles under high-voltage environment or respond to emergencies, it can quickly disconnect the connection of high-voltage circuits to make maintenance and other work in a safer state, such as external short-circuit conditions For protection, the high voltage needs to be disconnected during maintenance. The basic principle of MSD: MSD is designed in the main circuit of Pack, built-in high-voltage fuse, and high-voltage interlock function. The fuse cuts off the high-voltage circuit when an external short-circuit occurs; when the high-voltage needs to be manually disconnected, the high-voltage interlock is disconnected first, and then the high-voltage circuit is disconnected. 2. The functions that MSD needs to have. In practical applications, the design requirements of MSD should also include functional requirements such as operating temperature range, load cutting capacity, chemical corrosion resistance, mechanical strength and reliability. 3. Elements to be considered when selecting MSD in Pack a: Designed in the middle of the pack battery, such as a 100 string battery pack, the MSD needs to be designed in the middle of the 50 string, in order to ensure that the total voltage is reduced when disconnect Function, the total voltage is cut into several lower voltages, which can reduce possible safety risks. b: After the Pack is installed, the MSD must be in the car, so that the passengers in the car can quickly cut off the high-voltage circuit in the car when they find a safety hazard. c: When selecting MSD, the following factors need to be considered: (1) Rated voltage: If the maximum voltage of PACK is around 400V, select DC450V or more; (2) Load continuous current: MSD's rated current should be greater than the load 2 times the continuous current; (3) Load peak current: The load peak current capacity of MSD needs to be greater than the load peak current; (4) Response time consideration: MSD fusing response time should be less than the adhesion time of the relay. Although MSD is only a small part of Pack, since this part is related to product safety, its selection is very important, and we need to make full consideration. 5. Example of MSD selection. The output power of the battery pack of a project requires a current of about 130Aa: Umax of the pack: 420V, and the rated voltage of the MSD needs to be greater than or equal to 450V. b: Consider the load continuous current: MSD can choose 350A Fuse (350A＞2*130A) c: Response time consideration: Umax: 420VDCR100mΩ, short-circuit current: Umax/DCRu003d4200A Statement: Some pictures and content of articles published on this site From the Internet, if there is any infringement, please contact to delete the previous article: Only by improving the power battery recycling system can the root cause of battery pollution be solved